High tunneling magnetoresistance and tunneling electroresistance in multiferroic tunnel junctions constructed by two-dimensional Mn ₂ P ₂ Se ₆ /Sc ₂ CO ₂ van der Waals heterostructures

Multiferroic tunnel junctions (MFTJs) exhibit considerable potential in non-volatile memory devices due to their multifunctional properties. In van der Waals heterostructures (vdWHs), the band structures can be modulated by reversing the polarization direction of ferroelectric materials, providing possibilities for developing novel MFTJs. The two-dimensional (2D) ferroelectric Sc₂CO₂and ferromagnetic Mn₂P₂Se₆are selected as an example to construct the vdWHs and then the MFTJs. Six possible vdWH configurations are considered based on the stacking type by moving the Mn₂P₂Se₆layer relative to the Sc₂CO₂layer and reversing the polarization direction of the ferroelectric Sc₂CO₂. According to the calculated binding energies, the two AC-vdWH configurations with polarization states P↑and P↓are selected for further studies. When the polarization of the ferroelectric layer switches from P↑to P↓, the AC-vdWH exhibits a transition behavior from metallic to semiconducting states. Based on this phenomenon, 2D lateral MFTJs are designed with AC-P↑and AC-P↓serving as tunneling barriers respectively and metallic material Mn₂S₂Se₆as electrodes. It is found that setting magnetic moments on the two electrodes antiparallel (M↑↓) can increase the transmission difference between AC-P↑MFTJ and AC-P↓MFTJs significantly, which leads to a enhanced tunneling electroresistance ratio as high as 621%. In addition, for each AC-P↑MFTJ and AC-P↓MFTJ, when the direction of magnetism on both sides of the electrodes changes from parallel (M↑↑) to antiparallel (M↑↓), there is a substantial change in the transmission spectrum, leading to high tunneling magnetoresistance (TMR) ratios. Particularly, at the Fermi level, the TMR value of the AC-P↑configuration is8.48×103%, higher than that of the AC-P↓configuration with the value of1.257×103%. Therefore, the Mn₂P₂Se₆/Sc₂CO₂vdWH with the AC stacking mode demonstrates substantial potential for high-performance MFTJ design and significant applications for high-density non-volatile memory devices.